Sewing machine needle threader



Aug 13, 1940- y J. c. LoUNsBuRY 2,210,943

SEWING MACHENE NEEDLE THREADER Filed July 17, 1939 ATTORNEYS Patented Aug. 13, 194@ John C. Lounsbury, Washington, D. C. Application Jury 17, 1939, serial No. 284,988

5 Claims.

This inventionrelates to sewing machine needle threaders, and has for an object to provide an attachment which may be used when the needle is to be threaded and which will accurately 5 thread the needle in a fraction of the time it would take'to thread the needle by hand.

A further object is to provide 'a device of this character which will not lock until the needle is inserted, and which in the eventv of trouble causedby kinking of the thread or any other reason, can be easily unlocked manually to free the needle Without breakage.

A further object is to provide a device of this character in which a single spring is employed to force the threading pin through the eye of the needle and return the pin to neutral position.

A further object is to provide a device of this character in which the trigger and the lL barboth' move in the'same direction, at the same time, s'o that there is very little compression on the spring, thus Ypromoting the long life of the spring.

A further object is to provide'a device of this character in which a single spring operates all the moving parts.

A further object is to provide a device of this character in which the trigger automatically lifts itself into position and locks if the needle is in proper position to be threaded and if the needle is not in proper place the L bar will instantly drop and automatically release the trigger.

A further object is to provide a device of this character in which the mechanical construction is such that the most pressure is exerted on the threading pin when the pin is forcing the thread through the eye of the needle, with very little resistance onvthe return stroke of the pin.

A further object is to provide a device of this character which receives different sizes of needles, which will center the needle accurately regardless of size, and which may be easily applied to the sewing machine and will employ an adjustable cam to bear against the long leg of the presser foot and dispose the device in proper position with relation to the path of the needle to properly thread the needle. i

With the above and other objects in view the invention consists of certain novel details of construction and combination of parts hereinafter fully described and'claimed, it'being understood that various modications may be resorted to within the scope of the appended claims Without departure from the spirit or sacricing any of the advantages of the invention.

In the accompanying drawing forming part of this specicationz Figure 1 is a rear elevation ofa sewing ma'- 5 chine needle threader constructed inv accordance with the invention.

Figure '2 is -a side 'elevation of the needle threader in applied position. l

Figure 3 is a top plan view of the needle 1U threader with a portion broken away to show the presser foot.

Figure 4 is a longitudinal sectional view taken on the line 4-4 of Figure 2 showing the thread-. I ing pin in neutral position. 15

Figure 5 is a view similar to Figure 41but showing the trigger in locked'position and the threading pin in position to thread the needle.

Figure 6 is a view similar to Figure 5r but showing the trigger at the moment of release 20 when the threading pin has pushed a loop of the thread through the eye of thel needle l to be clamped stationary While the needle makes its up Figure '7 is a detail sectional View showing the 25 threading pin pushing a loop of` the thread against the bottom of the longitudinal groove of the needle.

Figure 8 is a detail sectional View showing the lthreading pin as having pushed a loop of the 30 thread through the eye of the needle. Y

Figure 9 is a detail sectional view showing the loop of the thread clamped stationary while the needle makes its up stroke after being threaded'.

Figure 10 is a detail side elevation of the 35 threading pin showing the concave tip to receive the thread. l

Figure 1l is a detail plan view showing'the shape of the needle receiving opening of the device to properly receive the needle and thread. 40

Referring now to the drawing in which like characters of reference designate similar parts in the various views, I0 designates the needle, II the presser foot stem, I2 the long leg of the presser foot, and I3 the short leg of the presser 45 foot, these being conventional sewing machine parts.

In carrying out the invention a substantially rectangular casing I4 is provided, open at the bottom and closed at the top by integral top wall 50 I5. A Abottom plate IB closes the bottom of the casing and is provided at the front end with forwardly and downwardly extending feet I1, and at the rear end with a rearwardly and downwardly extending foot I8 to support the device on the 55 sewing machine I9 above the conventional toothed leed 20 of the sewing machine, as best shown in Figure 2.

A gauge plate 2| is disposed on the bottom of the bottom plate I6 and is provided at the front end with depending lugs 22 which engage the sewing machine on opposite sides of the feed 20 and space the device thereabove. The gauge plate is provided with an integral upstanding guide pin 23, best shown in Figures 1 and 2, adapted to enter between the presser feet I2 and I3, as best shown in Figure 3. The gauge plate is provided centrally with a vertical wall portion 24 having an opening 25 therein to permit the long leg I2 of the presser foot to pass therethrough for engagement with a cam 26, best shown in Figure 2.

The cam 26 is provided with an eccentric cam surface 21, and is mounted on a cylindrical pin 28 which rises from the bottom plate I6. A screw 29 is passed through the pin 28, upper horizontal portion 3|) of the gauge plate, and bottom plate I6 of the casing, and is threaded into the top wall I5 of the casing. Dowel pins 9 on the bottom plate are engaged in the casing wall to coact with the screw in assembing the parts.

Formed integral with the casing is a partition Wall 3| having an opening 32 formed vertically therein and opening through the top Wall and bottom plate to receive the needle I0. A V shaped opening is formed in the front wall of the casing to provide converging guide surfaces 33 adapted to direct a loop of the thread 34 into the needle receiving opening 32, as best shown in Figures 3 and 11. The needle receiving opening 32 is provided with a V shape extension 35 to receive the needle. Opposite the extension the opening 32 is provided with a slot 36. The loop of the thread lodges in this slot and is thus properly positioned with respect to the eye of the needle to be pushed through the eye by the threading pin.

The threading pin 31, as shown in detail in Figure 10, is provided with a concave surface 38 at its tip to receive the thread. 'Ihe threading pin is slidably received in an opening 39 formed through the division Wall 3|.

An L shaped lever 40 is pivoted at its elbow.'

as shown at 4|, near one rear corner of the casing. 'I'he long leg of the L shaped lever is engaged through an opening 42 in the threading pin, the walls of the opening being reversely curved, as shown in Figure 10, to permit the threading pin rocking relatively to the needle during its rectilinear movement through the opening 39.

A trigger 43 is pivotally mounted on a pivot pin 44 which rises from the bottom plate I6 of the casing between the threading pin and the pivot pin 4I of the L shaped lever, and latterly of the L shaped lever. A slot 45 is formed in the trigger to receive this pivot pin so that the trigger may have rectilinear as well as pivotal movement. The trigger is provided with a right angularly disposed extension 46 which projects from the inner end of the trigger and in one position of the trigger engages the division wall 3| for a purpose which will be presently explained. The trigger is provided in its rear longitudinal edge with a bayonetslot 41 which receives a hook 48 which projects from the edge of an opening 49 in the rear wall of the casing. Through this latter opening the trigger projects exteriorly of the casing.

A U shaped spring 50 is engaged around and spaced from the assembly screw 29. One leg of the spring is secured to the trigger near the slot 41 and the other leg of the spring is securedto the short free leg of the L shaped lever. This spring transmits movement of the trigger to the L shaped lever and threading pin as will be presently described.

A substantially arcuate catch 5| is pivotally mounted on a pivot pin 52 which rises from the bottom plate of the device on the opposite side of the partition wall 3| from the L shaped lever. One end of the catch bears against the trigger 43 adjacent the extension 46. The opposite end of the catch forms a jaw 53 which coacts with a xed jaw 54 on the inner face of the front wall of the casing to clamp the loop of the thread stationary after the needle has been threaded by the threading pin.

In operation the device is placed with the legs I1 and I8 on the sewing machine and slid forwardly on the feed 20 with the guide pin 23 engaged between the presser feet I2 and I3 until the presser foot I2 engages the cam 26. The eccentric surface 21 of the cam automatically disposes the device with its longitudinal median line disposed obliquely to the central median line of the feed 20 in which position the threading pin is properly located to pass accurately through the eye of the needle. l

The y wheel of the sewing machine is then turned to lower the needle III through the opening 32, as shown in Figure '7. The operator then pulls the trigger from the position shown in Figure 4 to the position shown in Figure 5 which is the locked or cocked position ready to operate. During this movement of the trigger the spring 58 has been placed under compression to exert pressure upon the short leg of the L shaped lever and cause the long leg of the lever to press the loop of the thread against the bottom of the longitudinal slot in the needle. Also at the same time the extension 46 has rockedthe arcuate catch 5| on its pivot to open the jaw 53 from the stationary jaw 54.

The fly Wheel is then turned back to raise the needle III through the opening 32. At the moment the eye 55 of the needle enters the opening 32 the tensioned spring 5I) urges the threading pin through the eye of the needle and the loop of the thread is carried between the open jaws 53 and 54 as shown in Figure 8.A Simultaneously the long leg of the L shaped lever strikes against extension 46 and pushes the trigger forwardly to unlock the hook 48 from the trigger as shown in Figure 6 and permit the spring 50 to expand and rock the trigger to the neutral position shown in Figure 4. During such movement the trigger pushes against the curved end of the catch 5I and rocks the catch on the pivot 52 to close the jaw 53 and bind the loop of the thread stationary against the jaw 54 as shown in Figure 9. Meanwhile at the moment the trigger clears the hook 48 the spring 5|) pushes against the trigger and swings the trigger extension 46 against the long leg of the L shaped bar to instantly withdraw the threading pin 31 to its neutral position so that the threaded needle I0 may continue its upward stroke clear of the threading device, as shown in Figure 9.

It will be noted that upon release of the trigger by the operation of the threading pin passing through the eye of the needle, the trigger and the L lever both move in the same direction at the same time during withdrawal stroke of the `pin so that there is very little compression on the trigger is automatic when the needle is in proper position but if the needle is not in place the L lever can move suiliciently to automatically release the trigger.

It will also be noted that the greatest spring pressure is exerted on the threading pin when the pin is forcing the thread through the eye of the needle and that very little expansion of the spring takes place during the return stroke of the pin.

Also the trigger is in position to be easily reached for unlocking of the device manually if the thread is kinked or otherwise distorted with a tendency to jam in the threading device.

From the above it is thought that the construction and operation of the invention will be fully understood without further explanation.

What is claimed is:

1. A sewing machine needle threader comprising a casing, means for spacing the casing above a sewing machine feed, a threading pin mounted to slide transversely in the casing, a guide means in the casing in the path of the pin and of the sewing machine needle for receiving a loop of thread, a lever connected to the pin for moving the pin to carry the loop through the eye of the needle, means for clamping the loop of thread stationary while the pin is being withdrawn after the needle is threaded, a trigger adapted to engage the lever and the loop clamping means mounted in the casing for pivotal and rectilinear movement and adapted to be manually cocked, means carried by the casing for releasably holding the trigger in cocked position, and a single spring connected to the lever and to the trigger adapted to be tensioned when the trigger is cocked and adapted to expand and release the trigger as soon as the threading pin passes through the eye of the needle and adapted to simultaneously move the lever to withdraw the pin from the needle and actuate the loop clamping means.

2. A sewing machine needle threader comprising a casing, means for spacing the casing above a sewing machine feed, means connected to the casing adapted to coact with the long and the short leg of the presser foot of a sewing machine for disposing the longitudinal median line of the casing oblique to the longitudinal median line of the feed, a threading pin mounted to slide transversely in the casing, a guide means in the casing in the path of the pin and of the sewing machine needle for receiving a loop of thread, a lever conriected to the pin for moving the pin to carry the loop through the eye of the needle, means for clamping the loop of thread stationary while the pin is being withdrawn after the needle is threaded, a trigger adapted to engage the lever and the loop clamping means mounted in the casing for pivotal and rectilinear movement and adapt-ed to be manually cocked, means carried by the casing for releasably holding the trigger in cocked position, and a single spring connected to the lever and to the trigger adapted to be tensioned when the trigger is cocked and adapted to expand and release the trigger as soon as the threading pin passes through the eye of the needle and adapted to simultaneously move the lever to withdraw the pin from the needle and actuate the loop clamping means.

3. A sewing machine needle threader comprising a casing, means for spacing the casing above a sewing machine feed, a threading pin mounted to slide transversely in the casing, a guide means in the casing in the path of the pin and of the sewing machine needle for receiving a loop of thread, an L-shaped lever pivoted at its elbow in the casing and having one leg connected to the threading pin for moving the pin to carry the loop of thread through the eye of the needle, a trigger pivotally and slidable mounted in the casing and having a lateral extension at the pivot adapted to move the lever in a direction to withdraw the pin from the needle after the threading operation, an arcuate catch pivotally mounted in the casing having a jaw at one end and adapted to clamp the loop of thread stationary against the casing and adapted at the other end to engage the trigger and the extension thereof for opening and closing the jaw, means carried by the casing for releasably holding the trigger in cocked position, and a single U-shaped spring connected to the other leg of the lever and connected to the trigger adapted to be tensioned when the trigger is cocked and adapted to expand and release the trigger as soon as the threading pin passes through the eye of the needle and adapted to simultaneously move the lever and the catch to withdraw the pin from the needle and to clamp the loop of thread.

4. A sewing machine needle threader comprising a casing, means for spacing the casing above a sewing machine feed, there being a guide opening in the casing adapted to receive the sewing machine needle, said opening having a V-shaped extension on one side to center the needle and having a slot diametrically opposite the V-shaped extension to receive a loop of thread vertically, a threading pin mounted in the casing to slide transversely through said opening and having a concave tip to receive the loop of thread and carry it through the eye of the needle, a lever connected to the pin for moving the pin to carry the loop through the eye of the needle, means for clamping the loop of thread stationary While the pin is being withdrawn after the needle is threaded, a trigger adapted to engage the lever and the loop clamping means mounted in the casing for pivotal and rectilinear movement and adapted to be manually cocked, means carried by the casing for releasably holding the trigger in cocked position,'and a single spring connected to the lever and to the trigger adapted to be tensioned when the trigger is cocked and adapted to expand and release the trigger as soon as the threading pin passes through the eye of the needle and adapted to simultaneously move the lever to withdraw the pin from the needle and actuate the loop clamping means.

5. A needle threading device for sewing machines having a presser foot provided with a short leg and a long leg, a feed below the presser foot, and a needle, comprising a casing, legs on the casing for spacing the casing above the feed,-a gauge plate connected to the casing adapted to be spaced above the feed, a pin rising from the gauge plate adapted to enter between the legs of the presser foot, a cam adjustably mounted on the gauge plate having an eccentric edge adapted to engage the end of the long leg of the presser foot and dispose the longitudinal median line of the casing oblique to the longitudinal line of thelfeed, a threading pin mounted to slide transversely in the casing, a guide means in the casing in the path of the pin and of the sewing machine needle for receiving a loop of thread, a lever connected to the pin for moving the pin to carry the loop through the eye of the needle, means for clamping the loop of thread stationary while the pin is being withdrawn after the needle is threaded, a trigger adapted to engage' the lever and the loop clamping means mounted in the casing for pivotal and rectilinear movement and adapted to be manuallyV cocked, means carried by the casing for releasably holding the trigger in cocked position, and a single spring connected to the lever and to the trigger adapted to be tensioned when the trigger is cocked and adapted to expand and release the trigger as soon as the threading pin passes through the eye of the needle and adapted to simultaneously move the lever to withdraw the pin from the needle and actuate the loof) clamping means.

JOHN C. LOUNSBU'RY. 

